1. Technical Field of the Invention
This invention generally relates to the field of communication systems and, more particularly, to a Voice over Internet Protocol (VoIP) gateway to gateway communication system for use in an Internet Protocol (IP) network.
2. Description of the Background Art
Voice over Internet Protocol (VoIP) is a technology that allows the transmission of voice using an Internet Protocol (IP) network, such as the Internet. For instance, a calling party places a call on a telephone set. The telephone set digitizes the voice signal and transmits the voice signal to a VoIP gateway servicing the calling party. The VoIP gateway, in turn, establishes a call with a VoIP gateway that services the called party.
Presently the International Telecommunication Union—Telecommunication Standardization Sector (ITU-T) Recommendation H.323 specifies the technical requirements for the packets transmitted between VoIP gateways. Each packet has a Real-time Transport Protocol (RTP) header for carrying real time services such as voice and video in a payload portion of the RTP packet, a payload identifier so that the receiving gateway can determine the type of information contained in the packet, and sequence numbers and timstamps for identifying the order of the packets. In addition, the RTP packet is encapsulated in a User Datagram Protocol (UDP) transport/Internet Protocol (IP) layer packet.
Unfortunately, RTP and UDP overheads are too large. For example, the UDP header is 40 bytes and the RTP header is 12 bytes. As conventional methods are used to reduce the size of the Internet Protocol (IP) voice payload from 64 kb/s to as low as 4 kb/s, the RTP and UDP comprise a larger portion of the data actually transmitted resulting in inefficiency when transporting packets between VoIP gateways.